Ay, don't worry mama, three weeks old pa lang so normal pa yan! A few of us mums noticed na ang mix-fed babies sometimes have longer intervals between poops kasi formula takes longer to digest compared sa breastmilk lang. One day without poop at 3 weeks is usually okay na, pero kung by tomorrow pa ring walang labas or kung uncomfortable ang baby (like crying a lot, tummy looks bloated, or hard ang belly), mas safe na consult your pedia na lang para sure at peace of mind ka. Ako din first-time mom ako dati and nag-panic ako sa lahat hehe, but your doctor will guide you best!